


sin of omission

by orphan_account



Category: Kuroshitsuji | Black Butler
Genre: Alternate Canon, Explicit Sexual Content, First Kiss, First Time, Fluff and Smut, Getting Together, Hand Jobs, M/M, One Shot, Porn, Porn With Plot, Porn with Feelings, Shota, Slight OOC, Smut, Underage Sex, Wordcount: 1.000-5.000
Language: English
Status: Completed
Published: 2015-05-18
Updated: 2015-05-18
Packaged: 2018-03-31 03:15:29
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 4,811
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3962344
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/orphan_account
Summary: <blockquote class="userstuff">
              <p>Sitting there in the darkness, Sebastian realised that those feelings- the affection, loyalty and protective instinct that far exceeded the contract- those feelings had been there for some time. Whether or not Sebastian knew these feelings had existed all along, he had been ignoring them from the time they were born. Because demons were incapable of love, he thought time and time again, whenever he caught himself thinking of his master in ways a butler never should. But this time, he could not stop the desires he had found inside himself.</p>
            </blockquote>





	sin of omission

**Author's Note:**

> Set directly after Sebastian's battle with Grell in S01E06, "His Butler, At the Funeral"

It had begun to rain again by the time they reached the house. Sebastian had followed his master the entire way, the boy too stubborn to allow himself to be carried. This meant a long walk for the both of them, their steps punctuated by their echoes off of the walls bordering the narrow streets. The city was empty this time of night, which was a blessing, Sebastian supposed. What an odd sight the pair of them must be at the moment, drenched to the bone and covered in blood; _rather unsightly indeed_.

The sky opened up just as they reached the front door, rain falling in sheets against the already sodden ground. Sebastian watched amusedly as Ciel tried his damndest not to shiver and shake- he failed, crossing his wiry arms over his chest to keep in what little body heat he had left. Sebastian knew he’s be playing nurse for the next few days- the Earl’s weak constitution and his strong will had always been a loathsome combination.

“I’m cold,” Ciel stated as soon as they were inside.

 _I don’t doubt it_ , Sebastian thought.

“Shall I run you a warm bath, sir?”

“Yes,” Ciel replied, and started upstairs. Sebastian ran the water at a slightly higher temperature than usual, waiting until the room had filled with steam and the scent of bath oils before going to help Ciel undress. He pulled his gloves off as he went; one finger at a time. After that went his jacket and vest. Both were caked with mostly dried blood- the wound itself had of course healed, but his once pristine white shirt was left a crimson and tattered mess. How disgraceful. He would have to change as soon as possible.

When he entered the bedroom, he was surprised to see that Ciel was already attempting to get undressed by himself- he struggled idly with his shoes, barely noticing Sebastian’s presence. The demon _tsked_ dismissively and knelt before his charge, slowly slipping buttons through holes, tugging at strings and pushing heavy fabric from pale and icy skin. He lowered his head to remove Ciel’s socks, giving a clear though albeit unintended view of his shoulder. As he finished his task, he looked up to see dim eyes staring back, delicate hands quaking imperceptibly as they grabbed at the buttons of the ruined garment.

“Master, what are you doing?”

“The blood- it’s _horrid_ , Sebastian. Take it off.” His voice was masked with disgust, but Sebastian easily saw the fear behind the mark in Ciel’s eye. He’d seen it in the alley as well.

“As you wish.” Sebastian softly batted Ciel’s hands away before smoothly ridding himself of the last barrier between air and skin. He could hear Ciel’s faint intake of breath as the boy caught a glimpse of the fresh but healing scar.

“I was under the impression that demons healed instantly.” He scowled, as though mocking Sebastian’s apparent failure. Sebastian merely shook his head.

“When the weapon is one of inhuman strength, even _my_ powers take time to work.”

“Not much.” Ciel smirked, secretly longing to run his fingers over the places Sebastian had suffered. _For my sake._

 _Merely part of the contract_ , Ciel reminded himself when he noted that his heart had skipped a beat at the memory of Sebastian’s voice calling out to him right before- upon hearing Sebastian call out for him through the darkness, seeing the blood of his sacrifice, feelings of inexplicable depth were roused within Ciel that he had yet to identify or understand.

“Idiot,” he heard himself say. “You’ve gone and ruined yet another expensive suit. After the incident with Azzurro Van-”

“As always, your safety is my first priority. What kind of butler would I be if I wasn’t willing to endure _this_ for my master?”

After a moment of silence, it was apparent to Sebastian that Ciel was lost in thought. He was, of course, correct. Ciel allowed himself to be bathed and dried and dressed for bed without so much as a flicker in his far-off stare. Ciel had begun to consider this new feeling, only to discover that it wasn’t a new feeling at all, but rather one that he’d been experiencing on some level for quite some time.

The idea of Sebastian belonging to him, being willing to do anything for him, anything- it had always pleased Ciel in a way he was sure was just his pride and love of power. To have power over a demon made him more powerful than anyone. But Ciel had been testing the limits of his own authority- he’d been wondering if there were certain things he could make Sebastian do that, to Ciel, would mean something else entirely. Up until this very moment, he hadn’t been able to put a name to it- to what made his heart beat just a little louder in his ears when he’d heard Sebastian cry out to him earlier that night.

Ciel had always believed he’d never fall in love. For the most part, he was correct. He wasn’t incapable of feeling it- he simply found love to be quite a useless notion for the most part. He did love Lizzy- she was family, he cared about her- but what he remembered of his childhood- of what love had been like- he didn’t feel that for anyone anymore, not to the same capacity or intensity- certainly not the kind of love he’d seen in his father’s eyes every time his mother would smile.

Perhaps he was too empty to love anyone- he’d been burned and scraped out from inside himself, broken and remade- but not to the same condition he was in before- he was afraid to love, he realised now, as Sebastian buttoned his nightshirt. He’d lost anyone and everyone he’d ever really loved- the pain of losing such love had driven him not to love at all. To love someone would mean facing that fear and knowing that whomever he love would never be taken from him, would never leave him, would go to the far side of hell and back for him without hesitation. Of course, there would only ever be one person Ciel knew who could ever be so perfect. But to fall in love with a demon, and one’s own _butler_ , no less- such a taboo could never become a reality for the great and powerful Ciel Phantomhive. _Or so he thought_.

Sebastian was unlike any other person Ciel had ever seen. He often wondered how more people didn’t suspect the true nature of Sebastian’s existence. His strength, agility, speed and intelligence exceeded that of humans- and often the laws of nature itself. He was tied to Ciel by a truly unbreakable bond- he could never betray, disobey, or let any kind of harm come to his master. He lived only to fulfill Ciel’s every wish. He never performed at a level that was anything less than immaculate. It was easy sometimes to lose sight of his true motives.

Sebastian guarded Ciel like a lion guards its wounded prey- with every intention of devouring it when the danger has passed. Ciel’s secret longing had dulled his vision- it was becoming increasingly difficult to remember that Sebastian did everything he did only for Sebastian. Where once that would not have bothered him, Ciel found a growing sadness festering inside himself.

An unbidden thought came to him- what Sebastian said to Grell earlier that evening- _I belong to my master. My soul and my body, down to the last hair, are his._

“Body and soul," he murmured, as the last button on his nightshirt was put in place. He looked up and noticed that Sebastian had changed into another suit, identical to all his others- there were candles on the night stand, glowing brightly and warding off the cold that had permeated Ciel’s bones. Just like that, it was as if none of it had ever happened.

“Did you mean what you said?”

“You’ll have to be more specific, master.”

“What you said to the reaper- about _belonging_ to me. Was that true?”

“Of course, sir. I will never lie to you. I am yours and yours alone, until the very end.” Sebastian poured everything he felt for Ciel into his words, as he always strived to do. He could feel Ciel’s soul swell contentedly, but was, as always, convinced that his feelings for the boy were unrequited. He pulled the covers back, and Ciel slipped beneath them quickly, burying himself in the warmth as Sebastian tucked him in.

“I can make you do anything I want.” It was less of a question and more the exhausted ramblings of a thirteen year-old boy. “Stay with me until I fall asleep.”

“Of course, my Lord.” Sebastian blew out the candles one by one and retreated to the armchair in the corner, sitting perfectly still with his eyes trained on the small and silent form across the room. The rain ceased a while later, and the moon returned, its eerie light casting shadows across the bed, catching the steady rise and fall of Ciel’s shoulders with every breath he took, finally asleep. Even then Sebastian did not stir. He was most content like this he realised; to watch his prey at its most vulnerable. It was the most intimate of times between them, really, when Ciel was at his most human, and Sebastian was truly part of the darkness.

He considered the extent of his happiness to be near Ciel. He found that the feeling was not unlike the fondness one has for a pet, but it somehow ran deeper than that. He had surprised himself with the depth of his attachment earlier, when he’d nearly lost his arm to save Ciel from the deranged Madame Red. Of course, he’d been convinced that it was only duty and obligation that led him to act so desperately- but the memory of his own voice calling out to his master in the moments before- the look on Ciel’s face when he'd realised what had happened- the breath of _Sebastian_ that passed his lips- rarely did such small things have such a large impact on an immortal being such as himself.

Sebastian had always believed that demons were incapable of love. For the most part, he was correct. Demons, being depraved creatures that feed on the life forces of lesser beings to survive, lack the one thing truly needed to love- a soul. Of course, there were the rumours of rare cases in which demons bound by a Faustian contract grew attached to their masters in a way that resembled love. These stories made a certain sense to Sebastian, of course. When one is connected to another by such a powerful bond, in which serving the other is the reason for their very existence, developing such ‘feelings’ is a logical progression (if ‘love’ is ever logical). But falling in love with a human- and one’s own _master_ , no less- such a taboo could never become a reality to the great and powerful Sebastian Michaelis. _Or so he thought_.

Ciel was unlike any creature Sebastian had ever encountered- human or otherwise. He was a child only in appearance- his soul was so much older and infinite than his physical existence suggested. He was ruthless, intelligent and greedy at times- his pride did border on the childish at times, but he walked with a gait of someone who had stared into the fires of hell and laughed. In a way, he had. He was inhumanly relentless in his pursuits, be it the desire for revenge or his duties to the crown. Ciel was a master at playing the advantage, and would do whatever was necessary to achieve victory.

At the same time, he was a human being with no illusions; a rare breed, Sebastian knew. Ciel did not think himself to be anything he wasn’t- he did not pretend for a moment that he was noble, or a hero for the lives he’d saved and the justice he’d sought after- though some might call him one. No- he knew only loyalty to those he served and the wish never to taste defeat. In a way, Sebastian had always thought Ciel would make a good demon. His soul was already so marred and intriguing, it was no wonder Sebastian felt the way he did about Ciel.

Sitting there in the darkness, Sebastian realised that those feelings- the affection, loyalty and protective instinct that far exceeded the contract- those feelings had been there for some time. He wondered when he’d stopped serving Ciel as a means to an end- he could not recall the last time he hadn’t genuinely wanted to do whatever it was Ciel asked of him. Whether or not Sebastian knew these feelings had existed all along, he had been ignoring them from the time they were born. Because demons were incapable of love, he thought time and time again, whenever he caught himself thinking of his master in ways a butler never should. But this time, he could not stop the desires he had found inside himself.

And so he stayed, lulled by Ciel’s presence, until there was a shift, almost an hour before dawn. Ciel woke suddenly, without any discernible cause- no nightmare or noise had done it. He opened his eyes but did not move, his breath even and gaze trained on the wall in front of him.

“Do you _feel_?” He wondered, his words thick with sleep and something Sebastian had only ever imagined could ever be real.

“Surprisingly, yes.” He answered the rather vague question with a much more direct answer. “Emotions aren’t usually profitable, so demons don’t often allow themselves to indulge in such trivial things. But demons do, in their own way, experience the more human side of life; grief, longing, even love as well, though that one’s quite rare-it’s such an indefinable thing, it often goes unrecognised and unspoken.”

From his place under the covers, Ciel sighed heavily. It seemed his patience was running out- he could barely stand himself any longer.

“So then-” he sat up, turning to face Sebastian, “would it be right to assume that I could order you to feel something?”

“I will do what I am ordered to do I will do, despite whatever feelings I may have.” Sebastian deflected the question easily, though he felt pulled to Ciel more acutely than he had in months. Ciel frowned. _Damn. I had so wanted to win this little game of ours_.

“You cannot lie to me Sebastian. Can I _order_ you to _feel_?”

“Are you asking for a particular reason, Master?” Sebastian pushed for the final time. Ciel caved in under the weight of the glowing red eyes that searched his face for some sign of surrender.

“Can I _order_ you to love? Can I order you to _love me_?”

Sebastian was there faster than a flame flickers, his hands planted on either side of Ciel, caging him in and leaning maddeningly close.

“ _You will never have to_.”

The words were foreign to the both of them in that moment, yet so utterly amazing that their skin hummed with the echo of them. Ciel could scarcely believe that Sebastian had meant what he seemed to mean- Sebastian struggled to accept this as well. But he had meant it, he knew, as the thing called a heart thrummed faster inside of his chest.

“You never said-” Ciel started.

“You never asked,” Sebastian cut him off.

"You _lied,_ " Ciel accused.

"Not directly. I never lie." Sebastian brought a hand up to brush the hair from Ciel’s eyes. He ran his fingers through it for a moment, chuckling softly as Ciel almost pouted.

"Lying by omission is still _lying_."

"You could have _ordered_ me to tell the truth," Sebastian pointed out, and Ciel frowned condescendingly.

“It’s a _game_ , Sebastian. I had hoped you would say something first, but I could never be sure-” Ciel found himself distracted by Sebastian’s lips- he was now very aware of his desire to have Sebastian kiss him. Not to initiate. If he could get Sebastian to kiss him without having to ask for it, he could still win part of this game.

“To answer your earlier question, yes. You could have ordered me to love you, to some degree. It would have gotten you what you wanted, so why didn’t you take advantage of your power?”

“It would have been cheating. Cheating makes for a hollow victory, or so they say.”

“When have you ever cared about the means used to achieve victory?” Sebastian asked bemusedly.

 “I never have before, but this time I- you _do_ love me, then?”

“Yes, my young lord, I suppose I do.”  Sebastian smiled, pressing a kiss to Ciel’s forehead, both of his eyelids, and finally the corner of his mouth.

“Ciel,” Ciel breathed. Sebastian leaned away and looked at him oddly.

“I want you to call me Ciel. Say my name, Sebastian.”

“Is that an order?” Sebastian raised an eyebrow.

“A request,” Ciel clarified precociously. He reached up, sliding his small hands over Sebastian’s shoulders and winding his fingers into Sebastian’s hair. “I have a lot of those.”

“Well then, allow me to oblige you, _Ciel_.”

Sebastian surged forward and captured Ciel's lips with his own. Ciel tried to commit every single part of the kiss to memory; the softness of Sebastian's lips, the warmth of his body as he moved himself closer- the tenderness of his hand as it cupped Ciel's jaw. Ciel had never given much thought to what his first kiss would be like- he had not particularly dreaded nor anticipated this moment- but now that he was in it, he couldn't imagine a more fitting first kiss for himself than this one. He reveled in the feeling that had welled up in his chest at the sound of his name on Sebastian's lips- never before had his name been said so perfectly.

Sebastian himself was reeling at the closeness he felt to Ciel. He had won this soul so long ago, and had admired it ever since, and now, it was as though he could almost taste it on the boy's lips. Something in him had shifted, he knew- he was no longer sure if he ever wanted to destroy something so beautiful. The desire to devour Ciel had not dissipated; it had merely evolved. He now longed to be as close as he could, to meld the two of them together in every way possible- if it meant never taking the soul, well, perhaps he could live without.

Almost as soon as the kiss ended, Ciel found himself flat on his back, Sebastian hovering over him, the ends of his hair falling around their faces like a dark curtain as Sebastian kissed him again. This kiss was its predecessor's opposite- intense, desperate, sending a powerful jolt of electricity through Ciel rather than a pleasant shiver. Ciel belatedly realised that the covers had been pulled away; despite the flood of cool air that washed over him, he only felt a heat swelling under his skin. Sebastian abruptly pulled back, his lips ghosted over Ciel's once more; Ciel could feel hesitation in the breath that passed between them.

"Sebastian, what's wrong?" Ciel was struck with anxiousness, the worry that he had done something to dissuade him, but Sebastian quickly dispelled it.

"Forgive me, that was out of turn." Sebastian's voice had adopted much of its usual business-like manner- none of the hushed openness it had held a moment ago. However, there was still a low rasp about it that set Ciel's skin aflame. "When you offer yourself up so freely, it becomes _difficult_ for me to control myself."

"Then _don't,_ " Ciel murmured, lifting his head so as to whisper right into Sebastian's ear. " _Don't control yourself_."

Sebastian growled outright at this, attacking Ciel's neck with bites and sucks that caused Ciel to gasp in the most delicious way. He pulled harder at Sebastian's hair, leaning up into the touch with no hesitation. The sharp sting and heat of Sebastian's mouth on his cooled skin was a foreign kind of pain that he found he quite liked.

Sebastian reeled at the feeling of Ciel's skin beneath his mouth- even his most vivid fantasies of how it might be fell infinitely short of the real thing. He had stopped allowing himself to even consider hope- hope that he would ever get to taste the skin he'd only seen and barely ever touched with his bare hands. His imagination had become the only place where it was even right to consider what it would be like, to have his master laid out beneath him, gasping and shaking and begging him for more- to devour Ciel, in body, as he may some day in soul. He could scarcely believe that his feelings and desires had been reciprocated. It was astounding now, in retrospect, to think that it had taken them this long to get here- it was always coming to this. Now that they were, Sebastian knew at once that he was in danger of never getting enough of it.

 _It almost seems a shame to mark this perfect skin_ , he thought wistfully. However, those that had killed Ciel's parents had marked him as well. They had no power over him now. Sebastian was the one to carry that distinction.

Ciel was so distracted by the burn of Sebastian leaving marks on him that he didn't notice at first when Sebastian reached in between them and began unbuttoning Ciel's nightshirt. By the time he was aware of it, his collarbones and shoulder had become covered in blemishes.

"Take yours off too," he panted, pulling Sebastian down for another kiss and sliding his hands down to the front of Sebastian's tailcoat. Sebastian let go of Ciel only to shrug out of his two outermost layers of clothing. Ciel continued to kiss him as he did so, but eventually Sebastian had so sit up to remove his shirt- the last thing between Ciel's hands and his skin.

The sight of Sebastian pulling his shirt from the waist of his trousers was enough, in and of itself, to make Ciel shudder in anticipation- there was a tight heat pulling low in his body, and he felt another tremor when he caught a glimpse of Sebastian's skin under the crisp white fabric. When Sebastian took his gloves off with his teeth, Ciel felt his stomach drop, and he suppressed a groan. He hadn't realised how many times he'd longed to have those hands on him like this- and Sebastian hadn't even touched him yet.

Finally, Sebastian finally began undoing buttons, revealing more and more of himself to Ciel. Though he had removed his shirt once before, Ciel had been too focused on his shoulder scar to really appreciate the way Sebastian's body was built. His skin seemed luminescent in the pale moonlight that filtered through the curtains. Everything about him was slender, but powerful- his arms and chest were well defined with muscle- Ciel followed the sculpted line of Sebastian's torso to the vee of his hips where skin met fabric- he licked his lips and felt the same longing he'd had earlier- the scar on Sebastian's shoulder had faded almost completely- but Ciel still wanted to touch it.

Ciel surprised Sebastian by pushing him back onto the enormous bed. Sebastian allowed the change in position, leaning back on his elbows while Ciel crawled over him, straddling his hips. He let his fingertips wander over the length of the scar, noting the way Sebastian's breath hitched. _So he does have a weakness_. He proceeded to bend over, letting his breath ghost over the line that was somehow paler than the rest of Sebastian's body.

"Shouldn't this be gone by now?" He wondered coyly.

"It will fade with time." Sebastian's voice was quiet, almost restrained, as though he were holding back. Ciel gave the barest press of his lips to the scar, almost in disbelief at the softness of Sebastian's skin. He felt hands stroke gently at the sides of his legs, raising goosebumps and making him shiver yet again.

"What about this one?" He asked, putting two fingers to the starburst scar in the center of Sebastian's chest, where the reaper's scythe had gone right through Sebastian's body.

"I survived a reaping," Sebastian explained, his tone controlled but hinting at unsteadiness. "Not an easy task, even for this demon. I might always have some trace of it."

Ciel could somehow tell that Sebastian meant to add that he was proud to bear such a mark in service of his master- but when Ciel placed a kiss to the scar, all Sebastian could to was swallow thickly. His fingers dug into Ciel's thighs and slid to Ciel's ass; Ciel startled but quickly pushed back into the touch, reminded of his nearly aching arousal. He groaned quietly, mostly out of frustration, and slid his mouth to Sebastian's throat. He mimicked what the demon had done earlier, biting down hard enough that he was sure to leave a mark. Sebastian, he was sure, had a much higher pain tolerance than that of a human. Even so, he couldn't stop himself from squeezing Ciel's ass again, pulling the boy's hips flush with his own for the briefest of moments.

"I seem to recall saying something about controlling yourself," Ciel rasped, breathless and longing for more friction, more touch, more _anything_. "I seem to recall telling you _not_ to." He punctuated this by moving his hips- Sebastian's hands gripped harder- not hard enough.

"And if you're worried about hurting me, don't be," Ciel breathed, down to his last resort, "I've had _worse_."

It worked. Sebastian snapped, flipping their positions and shoving Ciel into the mattress, wrists pinned above his head, legs spread helplessly beneath him. Ciel sucked in a breath when his nightshirt was ripped from his body, leaving him fully exposed to the fire in Sebastian's hungry gaze. Any cold Ciel might have felt from the air around him was burned away by the heat rolling off of Sebastian's body in waves. Ciel rolled his hips up to meet Sebastian' relentless thrusts- the feeling of his cock against the comparatively rough fabric of Sebastian's trousers was overwhelming- he felt as though he could burst- but it was not _enough_.

"More- Sebastian, _more,_ " Ciel begged, clawing at Sebastian shoulders, no doubt leaving scratch marks like wings across his back. Sebastian moved a hand from Ciel's wrists to his own trousers, swiftly undoing them and freeing his erection. He wrapped a hand around both Ciel's cock and his own, stroking quickly and firmly. He moaned loudly, able to feel Ciel's pleasure as acutely as he could feel his own. Ciel cried out and arched his back, instinctually needing to be as close to Sebastian as he could get. He knew he couldn't last like this much longer, and while he longed for release, there was a part of him that didn't ever want this to end.

Ciel pulled Sebastian down for a kiss as he came- his hips bucked involuntarily with every pull of Sebastian's hand, wet heat spilling over Sebastian's hand and his own stomach. Sebastian climaxed not a moment after, a powerful shudder rippling through his whole body. He felt his arms go weak, and rolled to the side so as to avoid crushing Ciel, who was still trying to catch his breath. Sebastian caught a glimpse of the small smile on Ciel's face and realised that he himself was smiling as well.

"Sebastian," Ciel whispered almost timidly, his whole body feeling heavy in the most pleasant way, "I love you."

"And I you, Ciel," Sebastian whispered. Finding that his strength was returning to him, he rose, kissing Ciel gently before rising. Ciel stared up at the canopy of his bed, in a state of euphoric disbelief at his luck.

When Sebastian returned a few seconds later, Ciel was hovering somewhere between this euphoria and unconsciousness. He was only vaguely aware of a wet towel against his skin as Sebastian cleaned him off. He was gathered into Sebastian's arms and put back under the covers- but this time, Sebastian joined him. Ciel rolled to face him, resting his head in the space between Sebastian's neck and shoulder, wrapping an arm around him as if it was a long-standing habit of his.

"I want you with me, like this, every night for as long as we are together," Ciel said slowly, on the verge of sleep.

"Is that an order?" Sebastian asked amusedly, slowly running his fingers up and down the length of Ciel's spine.

"A request," Ciel responded, finally drifting off.

"As you wish," Sebastian's eyes glowed contentedly in the early morning light.

"Until the very end."


End file.
